1. Field of the Invention
The present invention relates to a card connection adaptor for connecting an IC card such as a memory card or a functional extension card to an information system such as a personal computer, or a portable information system represented by a PDA (personal digital assistant), a digital still camera and a digital video camera.
2. Description of Related Art
Recent notebook PCs (personal computers) are generally equipped with PC card slots. Functional extension of such a notebook PC can be achieved by inserting a PC card into the PC card slot. Exemplary PC cards include flash memory cards, modem cards and SCSI cards.
The PC cards are designed in compliance with the PC Card Standard, and classified into three types which have thicknesses of 3.3 mm (Type I), 5.0 mm (Type II) and 10.5 mm (Type III), respectively, with a rectangular plan shape of 54.0-mm width and 85.6-mm length.
For smaller-size information systems such as digital cameras, electronic organizers and portable phones, smaller-size CF (CompactFlash (registered trade mark) ) cards are employed instead of the PC cards to meet a heavy demand for size reduction. Typical examples of the CF cards are flash memory cards which are employed to store image data picked up by digital cameras and schedule data and address data for electronic organizers.
The CF cards are designed in compliance with the CFA (CompactFlash Association) Standard and classified into two types which have thicknesses of 3.3 mm (Type I) and 5.0 mm (Type II), respectively, with a rectangular plan shape of 36.4-mm width and 42.8-mm length.
Further, the digital cameras, digital voice recorders and portable phones employ small-size memory cards adapted only for memory functions. Such a small-size memory card includes a memory IC die packaged by resin-sealing, and is characterized by its extremely small thickness. Examples of the small-size memory cards include SmartMedia (SM (registered trade mark)), Miniature Card, MemoryStick and MultiMedia Card.
These cards have outer dimensions as shown below.
SmartMedia (SM): 37 .times. 45 .times. 0.76 (mm) Miniature Card (MC): 38 .times. 33 .times. 3.5 (mm) MemoryStick (MS): 50 .times. 21.5 .times. 2.8 (mm) MultiMedia Card (MMC): 32 .times. 24 .times. 1.4 (mm)
Since the smaller-size information systems do not always have a sufficient data processing capability, it is often necessary to load image data picked up by a digital camera into a notebook PC for editing the data or to transfer data between an electronic organizer and a notebook PC.
However, when data retained in the small-size information system is to be loaded into the notebook PC via a CF card or a small-size memory card, for example, such a card cannot directly be fitted in the PC card slot of the notebook PC because the PC card slot is designed in compliance with the PC Card Standard.
Therefore, card connection adaptors are conventionally provided for connecting a CF card or a small-size memory card to a PC card slot.
Such a card connection adaptor includes a housing having a shape conformal to the PC card, a first connector provided on a front edge of the housing for connection to a PC card slot, and a second connector provided within the housing for connection to a CF card or a small-size memory card. A card retaining space for receiving the CF card or the small-size memory card is provided within the housing. The card retaining space opens to a rear face of the housing as seen in an insertion direction in which the card connection adaptor is inserted into the PC card slot. Where the small-size card has a thickness close to the thickness of the card connection adaptor, the card retaining space may also open to the upper and/or lower side of the housing. In any case, the small-size card is inserted into the card connection adaptor from the rear side of the card connection adaptor in the same direction as the adaptor insertion direction in which the card connection adaptor is inserted into the PC card slot.
However, this arrangement has drawbacks from mechanical and electrical viewpoints. More specifically, when the card connection adaptor is fitted in the PC card slot, a rear portion of the small-size card fitted in the card connection adaptor is exposed from an opening of the PC card slot. Hence, there is a possibility that the small-size card is disconnected from the card connection adaptor by some external force. If the small-size card is disconnected during data transfer between the information system and the small-size card, the data transfer is of course failed, and destruction of date or destruction of elements inside the small-size card due to erroneous signal input may result. This is particularly problematic in the case of a card (e.g., a LAN card or a modem card) which is designed for leading signal input/output interconnections therefrom. Further, it is difficult to provide a retention mechanism in the card connection adaptor for assuredly holding the small-size card, whereas it is easy to provide a retention mechanism in the PC card slot for holding a card inserted therein.
Since it is physically possible to insert the small-size card into the card connection adaptor from the rear side thereof with the card connection adaptor fitted in the PC slot card, a user may make an attempt to insert the small-size card into the card connection adaptor in this state. In such a case, a great external force is exerted onto the connector of the PC card slot, so that the connector may be damaged.
In addition, there is a possibility that the small-size card is inserted into or withdrawn from the card connection adaptor fitted in the PC card slot when the information system is energized. Therefore, in designing the card connection adaptor, a consideration should be given to prevent the small-size card from being damaged by so-called active card insertion and withdrawal. More specifically, connection terminals of the card connection adaptor should accurately be positioned so that connection terminals of the small-size card can be connected to or disconnected from the connection terminals of the card connection adaptor in substantially the same connection/disconnection order and in substantially the same connection/disconnection timing when the small-size card is inserted into or withdrawn from the card connection adaptor. When the small-size card is to be inserted into the card connection adaptor, for example, connection of a grounding terminal, a source terminal, a first signal terminal, a second terminal and so forth should be established in the order named within an allowable connection timing range. It is, therefore, extremely difficult to design the card connection adaptor which can provide a guarantee against the active insertion and withdrawal.